This was discussed in the webinar. You can go to www.sewingonline.sulky.com
to register for the event and log into our new webinar/videocast platform. You will need to sign-up and choose a password. This Espadrilles webinar is free. Once you register for it (or any of the other webinars or videocasts available there) it will remain in your "My Library" for easy access anytime at the above website. You do need to register for each one individually.
This was first aired in May 2020, but I do remember that Melissa talked about the width adjustment. I suggest you get in touch with her after you watch the webinar to address this issue (and I saw your question about orthotics, too - she would be the best person to advise you).
You can contact the designer, Melissa Quaal at www.ahappystitch.com